In computer graphics applications, complex shapes and structures are formed through the sampling, interconnection and rendering of more simple objects, referred to as primitives. An example of such a primitive is a triangle, or other suitable polygon. These primitives, in turn, are formed by the interconnection of individual pixels. Color and texture are then applied to the individual pixels that comprise the shape based on their location within the primitive and the primitives orientation with respect to the generated shape; thereby generating the object that is rendered to a corresponding display for subsequent viewing.
The interconnection of primitives and the application of color and textures to generated shapes are generally performed by a graphics processor. Conventional graphics processors include a series of shaders that specify how and with what corresponding attributes, a final image is drawn on a screen, or suitable display device. As illustrated in FIG. 1, a conventional shader 10 can be represented as a processing block 12 that accepts a plurality of bits of input data, such as, for example, object shape data (14) in object space (x,y,z); material properties of the object, such as color (16); texture information (18); luminance information (20); and viewing angle information (22) and provides output data (28) representing the object with texture and other appearance properties applied thereto (x′, y′, z′).
In exemplary fashion, as illustrated in FIGS. 2A-2B, the shader accepts the vertex coordinate data representing cube 30 (FIG. 2A) as inputs and provides data representing, for example, a perspectively corrected view of the cube 30′ (FIG. 2B) as an output. The corrected view may be provided, for example, by applying an appropriate transformation matrix to the data representing the initial cube 30. More specifically, the representation illustrated in FIG. 2B is provided by a vertex shader that accepts as inputs the data representing, for example, vertices Vx, Vy and Vz, among others of cube 30 and providing angularly oriented vertices Vx′, Vy′ and Vz′, including any appearance attributes of corresponding cube 30′.
In addition to the vertex shader discussed above, a shader processing block that operates on the pixel level, referred to as a pixel shader is also used when generating an object for display. Generally, the pixel shader provides the color value associated with each pixel of a rendered object. Conventionally, both the vertex shader and pixel shader are separate components that are configured to perform only a single transformation or operation. Thus, in order to perform a position and a texture transformation of an input, at least two shading operations and hence, at least two shaders, need to be employed. Conventional graphics processors require the use of both a vertex shader and a pixel shader in order to generate an object. Because both types of shaders are required, known graphics processors are relatively large in size, with most of the real estate being taken up by the vertex and pixel shaders.
In addition to the real estate penalty associated with conventional graphics processors, there is also a corresponding performance penalty associated therewith. In conventional graphics processors, the vertex shader and the pixel shader are juxtaposed in a sequential, pipelined fashion, with the vertex shader being positioned before and operating on vertex data before the pixel shader can operate on individual pixel data.
Thus, there is a need for an improved graphics processor employing a shader that is both space efficient and computationally effective.